Cross-Platform

Cross-Platform Spreads

Spread endpoints are the fastest way to find price gaps between Kalshi and Polymarket. Use /spreads for the full scanner with filters, or /spreads/top for the ranked leaderboard.

Get API Key Open Dashboard

Real response from production APICross-platform spread example

Find live Kalshi/Polymarket price gaps

This request returns real data captured from production. Prices and spreads change over time.

Request

curl 'https://api.thepredictionmarkets.com/api/v2/spreads/top?limit=5&window=24' \
  -H 'X-API-Key: YOUR_TPM_API_KEY'

Response200 OK

{
  "data": [
    {
      "event_slug": "top-artist-on-spotify-us-in-2026",
      "event_title": "Top Artist on Spotify U.S. in 2026?",
      "outcome_title": "Drake",
      "platform_a": "polymarket",
      "platform_b": "kalshi",
      "price_a": 0.1055,
      "price_b": 0.79,
      "spread_bps": 6845,
      "confidence": 0.628,
      "is_stale": false,
      "updated_at": "2026-04-22T02:30:53.049830",
      "platform_a_url": "https://polymarket.com/event/top-spotify-artist-2026",
      "platform_b_url": "https://kalshi.com/markets/kxtopartistusa",
      "matching_strategy": "normalized_title_fallback",
      "match_quality": "auto_medium"
    },
    {
      "event_slug": "which-bills-will-become-law-in-2026-1",
      "event_title": "Which bills will become law in 2026?",
      "outcome_title": "Credit-card routing competition",
      "platform_a": "kalshi",
      "platform_b": "polymarket",
      "price_a": 0.08,
      "price_b": 0.44,
      "spread_bps": 3600,
      "confidence": 0.628,
      "is_stale": false,
      "updated_at": "2026-04-22T02:30:53.049830",
      "platform_a_url": "https://kalshi.com/markets/kxbills",
      "platform_b_url": "https://polymarket.com/event/which-bills-will-become-law-in-2026",
      "matching_strategy": "normalized_title_fallback",
      "match_quality": "auto_medium"
    }
  ],
  "count": 2
}

GET/api/v2/spreadsTry It

Find cross-platform spreads

The full spread scanner. Filter by event, minimum spread, volume threshold, platform, and staleness cutoff. Returns all qualifying cross-platform price gaps.

Live GET Request

Try it

Request URLX-API-Keymin_spreadmin_volume

Live Response

Click Try It to run this GET request against the API.

Request

curl 'https://api.thepredictionmarkets.com/api/v2/spreads?min_spread=0.05&min_volume=5000&stale_cutoff_minutes=60' \
  -H 'X-API-Key: YOUR_TPM_API_KEY'

Response

{
  "data": [
    {
      "event_slug": "top-artist-on-spotify-us-in-2026",
      "event_title": "Top Artist on Spotify U.S. in 2026?",
      "outcome_title": "Drake",
      "platform_a": "polymarket",
      "platform_b": "kalshi",
      "price_a": 0.1055,
      "price_b": 0.79,
      "spread": 0.6845,
      "spread_bps": 6845,
      "confidence": 0.628,
      "is_stale": false,
      "matching_strategy": "normalized_title_fallback",
      "match_quality": "auto_medium"
    }
  ],
  "count": 1
}

Query Parameters

Name	Type	Required	Default	Example	Description
event_slug	string	No	-	top-artist-on-spotify-us-in-2026	Filter to one event slug.
min_spread	number	No	0.02	0.05	Minimum spread in probability points (0.02 = 2%).
min_volume	number	No	1000	5000	Minimum platform volume in dollars.
platforms	string	No	-	polymarket,kalshi	Comma-separated platform slugs to include.
stale_cutoff_minutes	integer	No	45	60	Minutes after which a quote is considered stale.

Response Fields

Field	Type	Example	Description
event_slug	string	top-artist-on-spotify-us-in-2026	TPM event slug for event detail and history routes.
event_title	string	Top Artist on Spotify U.S. in 2026?	Market or event title.
outcome_title	string	Drake	Outcome being compared across venues.
platform_a	string	polymarket	Platform slug with the lower price.
platform_b	string	kalshi	Platform slug with the higher price.
price_a	number	0.1055	Normalized probability on platform_a (0 to 1).
price_b	number	0.79	Normalized probability on platform_b (0 to 1).
spread	number	0.6845	Absolute price difference as a decimal.
spread_bps	number	6845	Price difference in basis points (spread × 10,000).
confidence	number	0.628	TPM composite score (0–1) factoring spread size, volume, liquidity, and freshness.
is_stale	boolean	false	True when one or both platform quotes exceed the stale cutoff.
updated_at	string	2026-04-22T02:30:53.049830	ISO timestamp of the most recent platform quote.
platform_a_url	string	-	Direct link to the market page on platform_a.
platform_b_url	string	-	Direct link to the market page on platform_b.
matching_strategy	string	-	How the cross-platform match was established: auto_canonical, manual_override, normalized_title_fallback, or event_key.
match_quality	string	-	Match confidence tier: manual, auto_high, or auto_medium.

GET/api/v2/spreads/topTry It

Get top cross-platform spreads

Returns the strongest current Kalshi/Polymarket spread opportunities ranked by confidence. Use this for dashboards and alerts.

Live GET Request

Try it

Request URLX-API-Keylimitwindow

Live Response

Click Try It to run this GET request against the API.

Request

curl 'https://api.thepredictionmarkets.com/api/v2/spreads/top?limit=5&window=24' \
  -H 'X-API-Key: YOUR_TPM_API_KEY'

Response

{
  "data": [
    {
      "event_slug": "top-artist-on-spotify-us-in-2026",
      "event_title": "Top Artist on Spotify U.S. in 2026?",
      "outcome_title": "Drake",
      "platform_a": "polymarket",
      "platform_b": "kalshi",
      "price_a": 0.1055,
      "price_b": 0.79,
      "spread": 0.6845,
      "spread_bps": 6845,
      "confidence": 0.628,
      "is_stale": false,
      "updated_at": "2026-04-22T02:30:53.049830",
      "platform_a_url": "https://polymarket.com/event/top-spotify-artist-2026",
      "platform_b_url": "https://kalshi.com/markets/kxtopartistusa",
      "matching_strategy": "normalized_title_fallback",
      "match_quality": "auto_medium"
    }
  ],
  "count": 1
}

Query Parameters

Name	Type	Required	Default	Example	Description
limit	integer	No	20	5	Number of opportunities to return.
window	integer	No	24	24	Freshness window in hours used for top-spread ranking.

Response Fields

Field	Type	Example	Description
event_slug	string	top-artist-on-spotify-us-in-2026	TPM event slug for event detail and history routes.
event_title	string	Top Artist on Spotify U.S. in 2026?	Market or event title.
outcome_title	string	Drake	Outcome being compared across venues.
platform_a	string	polymarket	Platform slug with the lower price.
platform_b	string	kalshi	Platform slug with the higher price.
price_a	number	0.1055	Normalized probability on platform_a (0 to 1).
price_b	number	0.79	Normalized probability on platform_b (0 to 1).
spread	number	0.6845	Absolute price difference as a decimal.
spread_bps	number	6845	Price difference in basis points (spread × 10,000).
confidence	number	0.628	TPM composite score (0–1) factoring spread size, volume, liquidity, and freshness.
is_stale	boolean	false	True when one or both platform quotes exceed the stale cutoff.
updated_at	string	2026-04-22T02:30:53.049830	ISO timestamp of the most recent platform quote.
platform_a_url	string	-	Direct link to the market page on platform_a.
platform_b_url	string	-	Direct link to the market page on platform_b.
matching_strategy	string	-	How the cross-platform match was established: auto_canonical, manual_override, normalized_title_fallback, or event_key.
match_quality	string	-	Match confidence tier: manual, auto_high, or auto_medium.

Build with TPM

Get your API key

Start with Kalshi and Polymarket market data, then add unified spreads, signals, alerts, and watchlists as your workflow grows.

Get API Key Read Quickstart